Promising results are being obtained from studies of molecules labeled with Lead-212 (Pb-212) as potential targeted radiotherapeutic agent against metastatic melanoma. According to the American Cancer Society approximately 60,000 people in the US will be diagnosed with melanoma this year, and 8,000 will die from this disease. For Pb-212 melanoma therapy to proceed to clinical trials, it requires an imaging surrogate for treatment planning and disease staging. The Federal Food and Drug Administration recommended Pb-203 be developed as the imaging companion, the subject of this application. To prepare for clinical trials, animal studies will demonstrate that Pb-203 imaging isotope is a viable substitute for the therapeutic Pb-212 label. Animal studies will be performed to determine the agent's affinity for tumor cells, biodistribution will be assessed. Additionally to satisfy FDA requirements for clinical trials and approved drug product, a Pb-203 production method will be developed so that the isotope can be produced to support Pb-212 based therapies. After successful completion of this Phase II SBIR, AlphaMed will have completed the preclinical animal work needed to support an IND application for using Pb-203 labeled [DOTA]-ReCCMSH as the imaging partner for its Pb-212 based melanoma therapy. To support other Pb-212 based therapies, AlphaMed will have its Pb-203 production method listed as a Drug Master File, available to be referenced in IND applications. Targeted radiotherapy has shown to be very effective in preclinical tests in treating metastatic melanoma, a deadly form of skin cancer that takes 8,000 lives a year in the US. To proceed to clinical trials, an imaging isotope of the same element as the therapeutic will be used for treatment planning. Successful completion of this grant application will demonstrate the proposed imaging isotope is suitable and an acceptable isotope production process is established. [unreadable] [unreadable] [unreadable] [unreadable]